Entity Format

Let's look at a simple Cake entity.

use sea_orm::entity::prelude::*;

#[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
#[sea_orm(table_name = "cake")]
pub struct Model {
    #[sea_orm(primary_key)]
    pub id: i32,
    pub name: String,
}

#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
pub enum Relation {
    #[sea_orm(has_many = "super::fruit::Entity")]
    Fruit,
}

impl Related<super::fruit::Entity> for Entity {
    fn to() -> RelationDef {
        Relation::Fruit.def()
    }
}

impl ActiveModelBehavior for ActiveModel {}

info

Do not delete the Relation enum or ActiveModelBehavior impl block even if they are empty.

Entity

The DeriveEntityModel macro does all the heavy lifting of defining an Entity with associating Model, Column and PrimaryKey.

Table Name

The table_name attribute specifies the corresponding table in the database. Optionally, you can also specify the database schema or database name by schema_name.

Column Names

By default, all column names are assumed to be in snake_case. You can override this behaviour for all columns in a model by specifying the rename_all attribute.

#[sea_orm(rename_all = "camelCase")]
pub struct Model { ... }

You can find a list of valid values for the rename_all attribute here

• camelCase
• kebab-case
• mixed_case
• SCREAMING_SNAKE_CASE
• snake_case
• title_case
• UPPERCASE
• lowercase
• SCREAMING-KEBAB-CASE
• PascalCase

Column

Column Name

You can override the column name by specifying the column_name attribute.

#[derive(DeriveEntityModel)]
#[sea_orm(table_name = "user", rename_all = "camelCase")]
pub struct Model {
    #[sea_orm(primary_key)]
    id: i32,
    first_name: String, // firstName
    #[sea_orm(column_name = "lAsTnAmE")]
    last_name: String, // lAsTnAmE
}

Column Type

The column_type attribute defines the database type backing the attribute. Usually you don't have to specify this, as it will inferred from the rust type. For example, i32 maps to integer and String maps to varchar by default. You can read more about type mappings in the next chapter.

pub quantity: i32,  // integer by default
#[sea_orm(column_type = "Decimal(Some((16, 4)))")]
pub price: Decimal, // have to specify numeric precision

Because Postgres does not natively support unsigned integer types, using unsigned types (such as u64) is not recommended if you want to maintain compatibility.

Additional Properties

You can add additional properties default_value, unique, indexed and nullable to a column.

If you specified a custom column_type for an optional attribute, you must also specify nullable.

#[sea_orm(column_type = "Text", default_value = "Sam", unique, indexed, nullable)]
pub name: Option<String>

These properties are used in create_table_from_entity to generate the table for the entity.

Cast Column Type on Select and Save

If you need to select a column as one type but save it into the database as another, you can specify the select_as and the save_as attributes to perform the casting. A typical use case is selecting a column of type citext (case-insensitive text) as String in Rust and saving it into the database as citext. One should define the model field as below:

#[sea_orm(select_as = "text", save_as = "citext")]
pub case_insensitive_text: String

Ignore Attribute

If you want to ignore a particular model attribute such that it maps to no database column, you can use the ignore annotation.

#[sea_orm(ignore)]
pub ignore_me: String

Primary Key

Use the primary_key attribute to mark a column as the primary key.

#[sea_orm(primary_key)]
pub id: i32

Auto Increment

By default, auto_increment is implied for primary_key column. Override it by specifying false.

#[sea_orm(primary_key, auto_increment = false)]
pub id: i32

Composite Key

This is usually the case in junction tables, where a two-column tuple is used as the primary key. Simply annotate multiple columns to define a composite primary key. auto_increment is false for composite key.

The max arity of a primary key is 12.

pub struct Model {
    #[sea_orm(primary_key)]
    pub cake_id: i32,
    #[sea_orm(primary_key)]
    pub fruit_id: i32,
}

Relation

DeriveRelation is a macro to help you implement the RelationTrait.

#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
pub enum Relation {
    #[sea_orm(has_many = "super::fruit::Entity")]
    Fruit,
}

If there are no relations, simply write:

#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
pub enum Relation {}

The Related trait connects entities together, such that you can build queries selecting both entities.

Learn more about relations in the Relation chapter.

Active Model Behavior

Hooks for different actions on an ActiveModel. For example, you can perform custom validation logic or trigger side effects. Inside a transaction, you can even abort an action after it is done, preventing it from saving into the database.

#[async_trait]
impl ActiveModelBehavior for ActiveModel {
    /// Create a new ActiveModel with default values. Also used by `Default::default()`.
    fn new() -> Self {
        Self {
            uuid: Set(Uuid::new_v4()),
            ..ActiveModelTrait::default()
        }
    }

    /// Will be triggered before insert / update
    async fn before_save<C>(self, db: &C, insert: bool) -> Result<Self, DbErr>
    where
        C: ConnectionTrait,
    {
        if self.price.as_ref() <= &0.0 {
            Err(DbErr::Custom(format!(
                "[before_save] Invalid Price, insert: {}",
                insert
            )))
        } else {
            Ok(self)
        }
    }

    /// Will be triggered after insert / update
    async fn after_save<C>(model: Model, db: &C, insert: bool) -> Result<Model, DbErr>
    where
        C: ConnectionTrait,
    {
        Ok(model)
    }

    /// Will be triggered before delete
    async fn before_delete<C>(self, db: &C) -> Result<Self, DbErr>
    where
        C: ConnectionTrait,
    {
        Ok(self)
    }

    /// Will be triggered after delete
    async fn after_delete<C>(self, db: &C) -> Result<Self, DbErr>
    where
        C: ConnectionTrait,
    {
        Ok(self)
    }
}

If no customization is needed, simply write:

impl ActiveModelBehavior for ActiveModel {}